Review Question - QID 109866

A 15-year-old boy presents to his primary care doctor for "eye pain." He has noticed his left eye hurting more over the past 4 days. He normally wears disposable contact lenses daily but could not wear them because of the heightened sensation of something foreign in his eye. He has noticed occasional sensitivity to light. He denies any headaches, changes in vision, or pain with eye movement. He further denies any frank ocular or oral discharge. His temperature is 98.6°F (37°C), blood pressure is 115/73 mmHg, pulse is 62/min, respirations are 12/min, and oxygen saturation is 99% on room air. An image of his left eye is seen in Figure A. Which of the following is the most likely diagnosis?